Title

Simple ways to calculate the empirical resonance energies of benzenoid hydrocarbons, their derivatives, and graphite

Document Type

Article

Publication Date

1-1-1967

Abstract

A very simple equation is presented which reproduces the empirical resonance energies of 12 different benzenoid hydrocarbons within an average of ±1.4%, a considerably better result than those obtained by the VB method (±11.0%) and the simple LCAO–MO methods including overlap (±5.1%) and neglecting overlap (±11.8%). In the cases of the larger polyacenes (9 hydrocarbons) for which experimental values of empirical resonance energies are not available, this equation provides nearly the same results as the LCAO–MO‐overlap method. A second equation is given which yields the electron delocalization energies, in units of γ, of 21 benzenoid hydrocarbons within an average of ±1.0%. Formulas, based on the first equation, are found for the empirical resonance energies of eight different sequences of benzenoid hydrocarbons (e.g. benzene, coronene, peri‐dodecabenzocoronene, etc.). As a check, these formulas are used to estimate the resonance energy, per gram atom, of graphite, with satisfactory results (12 kcal versus the literature value of 10). It is then shown that the empirical resonance energies of benzenoid hydrocarbon derivatives can be determined by making use of group corrections to the calculated values of the empirical resonance energies of benzenoid hydrocarbons. The average error of the empirical resonance energies calculated by this method for 44 compounds was ±0.8 kcal/mole or ±1.5%. Copyright © 1967 John Wiley & Sons, Inc.

Publication Title

International Journal of Quantum Chemistry

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